How to Choose Bulbs for Containers

By Bill Marken, Suzanne DeJohn, and The Editors of the National Gardening Association from Container Gardening For Dummies, 2nd Edition

When choosing bulbs to plant in container gardens, planting just one bulb variety per pot ensures that all the bulbs in the pot will bloom at the same time. Mixing varieties in a container, on the other hand, results in flowers coming at different times, which has much less impact. If you want different flower colors and bloom times, grow different varieties in separate containers.

Bulbs look fine in a wide variety of container shapes and styles. As a general rule, spring bulbs are planted in the ground at a depth three times their diameter, but that rule doesn’t have to apply to short-term container growing. Choose containers that allow at least 2 inches of soil beneath the bulbs.

The traditional container in which to grow spring-blooming bulbs like hyacinths is a clay or plastic bulb pan, a shallow pot l0 inches or larger in diameter and only 5 or so inches deep. These pots don’t hold much soil, so they aren’t candidates for replanting with other flowers.

You can buy bulbs at a local nursery or garden center or by mail order. The nursery bins and bags give you a chance to personally inspect the bulbs for quality — always important! But perhaps more than any other plant, durable and compact bulbs lend themselves to mail-order delivery.

When you order from reputable suppliers, you can rest assured that you’ll receive high-quality bulbs. And you know that they’ve been stored in the proper conditions, usually a cool warehouse, rather than sitting out in an overheated store display. Plus, mail order generally offers the widest selection of varieties. Keep these tips in mind as you shop for bulbs:

Buying earlier is better: When you pick out your bulbs as soon as they hit the nurseries or catalogs, you get a much better selection of varieties. And at this time, the bulbs aren’t picked over, with just the runts remaining. If you’re not yet ready to plant, keep your bulbs in a cool dark place, with good air circulation and temperatures ideally between 35 and 50 degrees Fahrenheit.

Don’t store bulbs and fruits together in an enclosed place. For example, if you store your bulbs in the refrigerator, don’t put them in the vegetable crisper alongside a bag of apples. Ripening fruits emit ethylene gas which can damage the bulbs.
Bigger is better: The size of the bulb indicates the amount of food stored to provide energy for later regrowth. Bigger bulbs (graded number 1 or called topsize or topgrade) usually produce bigger flowers, more flowers, and taller, thicker stems than smaller bulbs, which are sometimes called landscape grade or field grade. Smaller bulbs at a good price may make sense if you plant them in the ground where they can develop over several years, but they aren’t a good choice for containers, where the bulbs usually can thrive only for one season.
Plump is better: Follow the same rule for choosing a bulb as you do for choosing a good grapefruit: The bulb should feel heavy for its size. A bulb that feels light may have lost moisture.
Firm is better: To what in the world does this rule not apply? You don’t want to buy rotting bulbs.
Two noses are better than one: This rule applies primarily to daffodils and perhaps some Picasso paintings. Daffodil bulbs develop noses, or little bulbs attached to the main bulb, each of which can produce leaves and flowers. Try to buy big fat bulbs with two or three noses.

For container-grown bulbs, you want a mix that’s well drained but that holds adequate moisture. Most commercial potting mixes work well. Because the bulb itself is a food storage structure, bulbs that grow only one season need little or no fertilizer. A soil mix that contains starter fertilizer is adequate, or you can mix in a small amount of bulb fertilizer at planting time.